BOULDER, Colo.— As atmospheric carbon dioxide levels hit a new record, Boulder has joined Santa Fe, Chicago and more than 25 other U.S. cities in supporting the use of the Clean Air Act to protect air quality and reduce greenhouse gas pollution to reduce the risk of runaway climate change. Through a resolution approved Tuesday night, Boulder has signed onto the Center for Biological Diversity’s national Clean Air Cities campaign, which urges the Environmental Protection Agency and President Barack Obama to take action on global warming through the Clean Air Act.

“Boulder’s leaders recognize that climate change will cost Colorado dearly, and they support one key solution: the Clean Air Act,” said Rose Braz, the Center’s climate campaign director. “Cities around the country, from Santa Fe to Tampa — and now Boulder — are sending an urgent message to our president and other national leaders: To avert a climate catastrophe, we need to act now.”

Arctic monitoring stations recently reported that carbon dioxide levels in the region have reached 400 parts per million — a milestone that underscores the risks posed by increasing concentrations of greenhouse gas pollution. Scientists say the world’s atmospheric carbon levels need to be reduced to 350 ppm to avoid disastrous climate change.

Climate change will increase Colorado’s risk of drought, heat waves and disastrous forest fires. It will also reduce snow pack and could knock as many as 30 days off the annual ski season, according to a 2008 report from the Center for Integrative Environmental Research.

Increased evaporation and other factors will reduce runoff to the Colorado River Basin by as much as 20 percent by mid-century, according to a 2008 scientific assessment commissioned by the Colorado Water Conservation Board.

Colorado’s biodiversity will also take a huge hit. Western trout populations, for example, could decline by as much as 64 percent, according to one scientific estimate. Mountain pine beetles and other tree pests and diseases will thrive under a warmer climate, posing a grave danger to the state’s forests.

The Center’s Clean Air Cities campaign is working with volunteers around the country to encourage cities to pass resolutions supporting the Clean Air Act and using the Act to reduce carbon in our atmosphere to no more than 350 parts per million. The resolutions call on President Obama and the EPA to take action under the Clean Air Act to address climate change.

Similar resolutions have been approved in Tampa and Pinecrest, Fla.; Cincinnati and Oberlin, Ohio; Chicago, Seattle, Wash.; Kansas City, Mo.; Albany, N.Y.; Tucson, Ariz.; Boone, N.C.; Philadelphia and Pittsburgh, Penn.; Minneapolis, Minn.; Santa Fe, N.M.; Cambridge, Mass.; Madison and Milwaukee, Wis., and Arcata, Richmond, Berkeley, Oxnard, Santa Cruz and Santa Monica, Calif. Several other cities around the country will be considering resolutions over the next few months.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 350,000 members and online activists dedicated to the protection of endangered species and wild places.